The present invention relates generally to a high efficiency refrigeration system and, more specifically, to a refrigeration system utilizing one or more vortex tubes for increasing the overall efficiency of a refrigeration system.
A refrigeration system typically consists of four major components connected together via a conduit (preferably copper tubing) to form a closed loop system. The four major components are a compressor, a condenser, an expansion device and an evaporator. A refrigerant will have its pressure either increased or decreased and its temperature either increased or decreased by the four components as it circulates therethrough.
The refrigerant is continuously cycled through the refrigeration system. The main steps in the refrigeration cycle are compression of the refrigerant by the compressor, heat rejection of the refrigerant in the condenser, throttling of the refrigerant in the expansion device, and heat absorption of the refrigerant in the evaporator. The compressor provides the energy to keep the refrigerant moving within the conduits and through the major components This process is sometimes referred to as a vapor-compression refrigeration cycle.
The vapor-compression refrigeration cycle is used in air conditioning systems, which cool and dehumidify air in a living space, in a moving vehicle (e.g., automobile, airplane, train, etc.), refrigerators and heat pumps.
During the refrigeration cycle, the refrigerant enters the compressor as saturated vapor and is compressed to a very high pressure. The temperature of the refrigerant increases during this compression step. The refrigerant leaves the compressor as superheated vapor and enters the condenser. A typical condenser comprises a single conduit formed into a serpentine-like shape so that a plurality of rows of conduit is formed parallel to each other. Metal fins or other aids are usually attached to the serpentine conduit in order to increase the transfer of heat between the refrigerant passing through the condenser and the ambient air. Heat is rejected from the superheated vapor as it passes through the condenser and the refrigerant exits the condenser as saturated liquid.
The expansion device reduces the pressure of the saturated liquid thereby turning it into a saturated liquid-vapor mixture, which is throttled to the evaporator. The temperature of the refrigerant drops below the temperature of the ambient air as it goes through the expansion device. The refrigerant enters the evaporator as a low quality saturated mixture comprised of approximately 20% vapor and 80% liquid. (xe2x80x9cQualityxe2x80x9d is defined as the mass fraction of vapor in the liquid-vapor mixture.)
The evaporator physically resembles the serpentine-shaped conduit of the condenser. Ideally, the refrigerant completely evaporates by absorbing heat from the refrigerated space and leaves the evaporator as saturated vapor at the suction pressure of the compressor and reenters the compressor thereby completing the cycle.
The efficiency of a refrigeration cycle is traditionally described by an energy-efficiency ratio (EER). It is defined as the ratio of the heat absorption from an evaporator to the work done by a compressor.   EER  =            Heat      ⁢              xe2x80x83            ⁢      absorption      ⁢              xe2x80x83            ⁢      from      ⁢              xe2x80x83            ⁢      evaporator              Work      ⁢              xe2x80x83            ⁢      done      ⁢              xe2x80x83            ⁢      by      ⁢              xe2x80x83            ⁢      compressor      
In a typical air conditioning system, the refrigeration cycle has an EER of approximately 2.0 (kw/kw).
The present invention is designed to increase the efficiency of a refrigeration, air conditioning or heat pump system by increasing the efficiency of the refrigeration cycle. The increase in the efficiency is achieved by assisting in the conversion of the refrigerant from vapor to liquid at specific points in the refrigeration cycle. In a preferred embodiment of the present invention, a first vortex tube is placed between the expansion device and the evaporator in order to increase the percentage of refrigerant entering the evaporator as a liquid, and a second vortex tube is placed between the evaporator and the compressor in order to increase the percentage of refrigerant entering the compressor as a vapor. Since the heat absorption from the evaporator occurs through the evaporation of the liquid refrigerant, the increase in the percentage of the liquid refrigerant entering the evaporator increases the efficiency of the refrigeration cycle and reduces the size of the evaporator.
Another way the present invention increases the efficiency of the refrigeration cycle is by placing a vortex tube in the serpentine tubing of the condenser. In the preferred embodiment, the vortex tube is placed approximately one-quarter of the way in from the inlet of the condenser where desuperheating is completed. Once again, the vortex tube produces liquid refrigerant and further increases the temperature of the vapor refrigerant thereby reducing the size of the condenser and decreasing the head pressure of the compressor. As a result, the compression ratio decreases, and the work required by the compressor is reduced, thus increasing the efficiency of the refrigeration cycle.